Not sure what your goal is, but probably what you need to do (in Unity at least) to click the png and do the following in the inspector. Change the "Texture type" to "Sprite (2D and UI)" if it's not so already. To remove the fuzzyness of the image use the "Filter mode" -> "Point (No filter)". Then press "Open Sprite Editor", and press "Slice", change "Type" ->"Grid by cell size" set "Pixel size" to 16 for both x and y. Press "Slice" and then "apply" in top right.